Cast aluminum alloys comprising calcium and related processes

Abstract

Described are processes for continuously casting aluminum alloys, wherein the alloys comprise or are modified to comprise Mg. The processes involve adding Ca to the molten aluminum alloy prior to casting in order to decrease surface defects and exudates in the cast aluminum alloys.

1 . A process for casting an aluminum alloy, comprising:
 melting an aluminum alloy to form a molten aluminum alloy, wherein the molten aluminum alloy comprises Mg;   adding at least 30 ppm Ca to the molten aluminum alloy; and   continuously casting the molten aluminum alloy to form a cast aluminum alloy.   
     
     
         2 . The process of  claim 1 , wherein the aluminum alloy does not comprise Mg, and wherein the process further comprises adding Mg to the molten aluminum alloy. 
     
     
         3 . The process of  claim 1 , wherein the aluminum alloy article is a 5xxx series aluminum alloy, a 6xxx series aluminum alloy, or a 7xxx series aluminum alloy. 
     
     
         4 . The process of  claim 1 , wherein the Ca is added to the molten aluminum alloy in an amount from 50 ppm to 500 ppm. 
     
     
         5 . The process of  claim 1 , wherein the Ca is added to the molten aluminum alloy in an amount from 50 ppm to 400 ppm. 
     
     
         6 . The process of  claim 1 , wherein the Ca is added to the molten aluminum alloy in an amount from 50 ppm to 250 ppm. 
     
     
         7 . The process of  claim 1 , wherein the Ca is added to the molten aluminum alloy in a trough of a continuous caster. 
     
     
         8 . The process of  claim 1 , wherein the molten aluminum alloy is substantially free of Be. 
     
     
         9 . The process of  claim 1 , wherein the cast aluminum alloy comprises at least 0.3% by weight Mg. 
     
     
         10 . The process of  claim 1 , wherein the cast aluminum alloy comprises an oxide surface layer. 
     
     
         11 . The process of  claim 1 , further comprising cooling the cast aluminum alloy upon exit from a continuous caster. 
     
     
         12 . The process of  claim 11 , wherein the cooling step comprises water quenching the cast aluminum alloy. 
     
     
         13 . The process of  claim 1 , wherein the cast aluminum alloy is coiled. 
     
     
         14 . The process of  claim 1 , further comprising:
 solutionizing the aluminum alloy article;   quenching the aluminum alloy article; and   aging the aluminum alloy article.   
     
     
         15 . The process of  claim 1 , wherein a cold rolling step is performed. 
     
     
         16 . An aluminum alloy article prepared according to the process of  claim 1 . 
     
     
         17 . The aluminum alloy article of  claim 16 , wherein the aluminum alloy article is an aluminum alloy sheet, an aluminum alloy plate, or an aluminum alloy shate. 
     
     
         18 . The aluminum alloy article of  claim 16 , wherein the aluminum alloy article is an automotive body part, a motor vehicle part, a transportation body part, an aerospace body part, or an electronics housing. 
     
     
         19 . The aluminum alloy article of  claim 16 , wherein the surface of the product has at least 10% less surface defects than a product formed without addition of calcium.